Multi-lane Coherent Transceiver Synchronized Lane Reset Signals
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Solution Overview
Problem
Multi-lane coherent transceivers face timing issues due to asynchronous reset signals, which can cause jitter and skew in clock startup timing across lanes, leading to different data orders.
Innovation Solution
A transceiver with synchronized lane reset signals is implemented using a reset synchronization circuit and time-to-digital converters to delay and synchronize reset signals, ensuring all lanes receive reset signals in sync with the high-speed clock, reducing timing discrepancies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If asynchronous reset signals are used in multi-lane coherent transceivers, then the device complexity is reduced and ease of operation is improved, but timing precision and data alignment between lanes deteriorate due to jitter and skew in clock startup timing
Solution Approach 1:
A dedicated reset synchronization circuit is introduced as an intermediary component between the state machine and the lanes. This circuit receives the asynchronous reset signal and outputs synchronized reset signals to each lane, mediating the timing discrepancy between the reset signal and the high-speed clock signals across different lanes.
Solution Approach 2:
The reset synchronization circuit performs preliminary synchronization of the reset signal before it reaches the lanes. By pre-aligning the reset signal timing with the high-speed clock signals, the system prevents timing issues from propagating to the data serialization process.
2Adaptability or versatility
If software or firmware controlled state machines generate reset signals, then adaptability and versatility are improved, but timing precision and reliability of reset signal synchronization deteriorate
Solution Approach 1:
The reset synchronization circuit serves as a reliable intermediary between the flexible but imprecise state machine and the timing-critical lane circuits. It maintains the adaptability of software-controlled reset generation while ensuring reliable timing synchronization through hardware-based clock alignment.
3Device complexity
If reset signals are not synchronized with high-speed clock signals, then device complexity is reduced, but manufacturing precision and data order consistency across lanes deteriorate
Solution Approach 1:
The reset synchronization circuit performs preliminary timing alignment of reset signals with high-speed clock signals before they reach the serialization logic. This pre-synchronization ensures that data ordering is established correctly from the start, preventing alignment issues without requiring complex post-processing circuits.
Data Source
AI summary
The reset signals output to the lanes of a multi-lane coherent transceiver are synchronized by first synchronizing an asynchronous reset signal to a low-speed clock signal to generate and output a plurality of synchronized reset signals to the lanes. Within each lane, a synchronous reset signal is delayed to generate a number of delayed synchronous reset signals, and the logic states of the synchronous reset signal and the delayed synchronous reset signals are captured. Based on the captured logic states in each of the lanes, a lane synchronized reset signal from the delayed synchronous reset signals is selected for use across all of the lanes.